Al-Storage Behaviors of Expanded Graphite as High-Rate and Long-Life Cathode Materials for Rechargeable Aluminum Batteries

The rational design and synthesis of capable cathode materials with low cost that can exhibit good electrochemical performance are key to the development of rechargeable aluminum batteries (RABs). In this article, we have developed low-cost expanded graphite as typical cathode materials for high-performance RABs in pouch cells. Remarkably, the commercial expanded graphite can show high-rate performance, long-term cyclic life, and high energy density (64 Wh kg-1 based on a whole pouch cell). In particular, it delivers a high capacity of 111 mAh g-1 at a current density of 2 A g-1 after 300 cycles and 61.1 mAh g-1 at a high current density of 50 A g-1 after 10 000 cycles. The high-rate performance is derived from the rapid kinetic enhancement caused by the chemisorption-involved-intercalation pseudocapacitance effect. Further, a series of facile electrochemical means are used to confirm the intercalation (1.5-2.4 V)-adsorption mechanism (0.5-1.5 V) of expanded graphite. This work can provide significant support for further understanding the Al-storage behaviors of graphite materials in RABs.